I'm wondering why we would want to make the instances a child of the duplicator instead of just leaving it parentless. Is it for organization purposes?
It depends what you're instantiating and for what purpose. If I'm instantiating a bunch of temporary enemy characters I may want to store them all within one parent. When I no longer need them I can just destroy the parent game object to remove them all. So it can be used solely for organization, or it can also be used more practically by ensuring all those objects are stored in one location so to speak.